Playlists on 4Stream App not working after restart of app

If I create a paylist in 4StreamApp from files on UPnP / DLNA-server, that playlist is no longer working after a restart of the app. It jumps through the titles very quickly without playing them. If I then add another title to the same (“broken”) playlist, it only plays that title. After another restart of the app, also theses newly added titles are no longer playable.

The problem is on H50 and Up2Stream Amp V4 devices. App runs on android mobile, DLNA-server is rapsberry pi with mini-dlna.

EDIT: with the WiiM-app it works perfectly, so the error is in the 4Stream app